/*!
 * Lazy Load - jQuery plugin for lazy loading images
 *
 * Copyright (c) 2007-2015 Mika Tuupola
 *
 * Licensed under the MIT license:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Project home:
 *   http://www.appelsiini.net/projects/lazyload
 *
 * Version:  1.9.7
 *
 */
(function ($, window, document, undefined) {
  var $window = $(window);
  $.fn.lazyload = function (options) {
    var elements = this;
    var $container;
    var settings = {
      threshold: 0,
      failure_limit: 0,
      event: "scroll",
      effect: "show",
      container: window,
      data_attribute: "original",
      skip_invisible: false,
      appear: null,
      load: null,
      placeholder: ""
    };

    function update() {
      var counter = 0;
      elements.each(function () {
        var $this = $(this);
        if (settings.skip_invisible && !$this.is(":visible")) {
          return;
        }
        if ($.abovethetop(this, settings) ||
          $.leftofbegin(this, settings)) {
          /* Nothing. */
        } else if (!$.belowthefold(this, settings) &&
          !$.rightoffold(this, settings)) {
          $this.trigger("appear");
          /* if we found an image we'll load, reset the counter */
          counter = 0;
        } else {
          if (++counter > settings.failure_limit) {
            return false;
          }
        }
      });
    }
    if (options) {
      /* Maintain BC for a couple of versions. */
      if (undefined !== options.failurelimit) {
        options.failure_limit = options.failurelimit;
        delete options.failurelimit;
      }
      if (undefined !== options.effectspeed) {
        options.effect_speed = options.effectspeed;
        delete options.effectspeed;
      }
      $.extend(settings, options);
    }
    /* Cache container as jQuery as object. */
    $container = (settings.container === undefined ||
      settings.container === window) ? $window : $(settings.container);
    /* Fire one scroll event per scroll. Not one scroll event per image. */
    if (0 === settings.event.indexOf("scroll")) {
      $container.bind(settings.event, function () {
        return update();
      });
    }
    this.each(function () {
      var self = this;
      var $self = $(self);
      self.loaded = false;
      /* If no src attribute given use data:uri. */
      if ($self.attr("src") === undefined || $self.attr("src") ===
        false) {
        if ($self.is("img")) {
          $self.attr("src", settings.placeholder);
        }
      }
      /* When appear is triggered load original image. */
      $self.one("appear", function () {
        if (!this.loaded) {
          if (settings.appear) {
            var elements_left = elements.length;
            settings.appear.call(self, elements_left, settings);
          }
          $("<img />")
            .bind("load", function () {
              var original = $self.attr("data-" + settings
                .data_attribute);
              $self.hide();
              if ($self.is("img")) {
                $self.attr("src", original);
              } else {
                $self.css("background-image", "url('" + original +
                  "')");
              }
              $self[settings.effect](settings.effect_speed);
              self.loaded = true;
              /* Remove image from array so it is not looped next time. */
              var temp = $.grep(elements, function (element) {
                return !element.loaded;
              });
              elements = $(temp);
              if (settings.load) {
                var elements_left = elements.length;
                settings.load.call(self, elements_left, settings);
              }
            })
            .attr("src", $self.attr("data-" + settings
              .data_attribute));
        }
      });
      /* When wanted event is triggered load original image */
      /* by triggering appear.                              */
      if (0 !== settings.event.indexOf("scroll")) {
        $self.bind(settings.event, function () {
          if (!self.loaded) {
            $self.trigger("appear");
          }
        });
      }
    });
    /* Check if something appears when window is resized. */
    $window.bind("resize", function () {
      update();
    });
    /* With IOS5 force loading images when navigating with back button. */
    /* Non optimal workaround. */
    if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
      $window.bind("pageshow", function (event) {
        if (event.originalEvent && event.originalEvent.persisted) {
          elements.each(function () {
            $(this).trigger("appear");
          });
        }
      });
    }
    /* Force initial check if images should appear. */
    $(document).ready(function () {
      update();
    });
    return this;
  };
  /* Convenience methods in jQuery namespace.           */
  /* Use as  $.belowthefold(element, {threshold : 100, container : window}) */
  $.belowthefold = function (element, settings) {
    var fold;
    if (settings.container === undefined || settings.container === window) {
      fold = (window.innerHeight ? window.innerHeight : $window.height()) +
        $window.scrollTop();
    } else {
      fold = $(settings.container).offset().top + $(settings.container)
        .height();
    }
    return fold <= $(element).offset().top - settings.threshold;
  };
  $.rightoffold = function (element, settings) {
    var fold;
    if (settings.container === undefined || settings.container === window) {
      fold = $window.width() + $window.scrollLeft();
    } else {
      fold = $(settings.container).offset().left + $(settings.container)
        .width();
    }
    return fold <= $(element).offset().left - settings.threshold;
  };
  $.abovethetop = function (element, settings) {
    var fold;
    if (settings.container === undefined || settings.container === window) {
      fold = $window.scrollTop();
    } else {
      fold = $(settings.container).offset().top;
    }
    return fold >= $(element).offset().top + settings.threshold + $(element)
      .height();
  };
  $.leftofbegin = function (element, settings) {
    var fold;
    if (settings.container === undefined || settings.container === window) {
      fold = $window.scrollLeft();
    } else {
      fold = $(settings.container).offset().left;
    }
    return fold >= $(element).offset().left + settings.threshold + $(
      element).width();
  };
  $.inviewport = function (element, settings) {
    return !$.rightoffold(element, settings) && !$.leftofbegin(element,
        settings) &&
      !$.belowthefold(element, settings) && !$.abovethetop(element,
        settings);
  };
  /* Custom selectors for your convenience.   */
  /* Use as $("img:below-the-fold").something() or */
  /* $("img").filter(":below-the-fold").something() which is faster */
  $.extend($.expr[":"], {
    "below-the-fold": function (a) {
      return $.belowthefold(a, {
        threshold: 0
      });
    },
    "above-the-top": function (a) {
      return !$.belowthefold(a, {
        threshold: 0
      });
    },
    "right-of-screen": function (a) {
      return $.rightoffold(a, {
        threshold: 0
      });
    },
    "left-of-screen": function (a) {
      return !$.rightoffold(a, {
        threshold: 0
      });
    },
    "in-viewport": function (a) {
      return $.inviewport(a, {
        threshold: 0
      });
    },
    /* Maintain BC for couple of versions. */
    "above-the-fold": function (a) {
      return !$.belowthefold(a, {
        threshold: 0
      });
    },
    "right-of-fold": function (a) {
      return $.rightoffold(a, {
        threshold: 0
      });
    },
    "left-of-fold": function (a) {
      return !$.rightoffold(a, {
        threshold: 0
      });
    }
  });
})(jQuery, window, document);
